Rock weathering plays an important role in soil development. A better understanding of how different temperature and moisture regimes impact on the rates of rock breakdown can thus contribute to our knowledge of how rates of soil production might be affected by changes in climate. Laboratory simulations using two temperature cycles determined from field data and three moisture levels were carried out on samples of granite from three locations along the Victoria Land coast. Estimates of weathering rate from these experiments were of the same order of magnitude as some other more field based studies undertaken in similar environments. However, actual values for samples from the three locations varied depending on the specific characteristics of the rock, especially grain size, porosity and extent of micro-cracking. Moisture availability was found to be an important factor in determining weight loss in the samples from Gneiss Point but not in those from Terra Nova Bay or Teall Island with the moderate level of moisture application having the greatest impact. Spring/autumn temperature cycles had a different effect on the breakdown of the rock samples compared to summer cycles but the magnitude of the effect was dependent on moisture level and rock characteristics, especially quartz content and the ability to absorb heat and moisture. The samples of rock from Terra Nova Bay and Gneiss Point where no moisture had been applied had significantly higher rates of breakdown under spring/autumn cycles than summer ones. However, this effect was reversed in the Gneiss Point samples after moisture was added. A future climate scenario using the weathering rates found in this research where there was, for example, a 10% increase in summer temperature cycles and a corresponding decrease in spring/autumn cycles predicted that a reduction in weathering would occur in conditions of little or no precipitation at Terra Nova Bay and Gneiss Point but there would be limited effect under higher levels of moisture.

Two shallow ponds at Cape Evans, Ross Island, were sampled at 1–2 week intervals, during winter freezing throughout the winter and during the subsequent melt period, to examine the physical and chemical conditions imposed on the biota during the year. Liquid water was first detected at the base of the ponds in late December. During the main summer melt period conductivities were less than 10 mS cm−1 with maximum daily temperatures around 5°C. The bottom waters became increasingly saline during freezing and water temperatures decreased below 0°C; by June the remaining water overlying the sediments had conductivities >150 mS cm−1 and temperatures of −13°C. Calcium carbonate, then sodium sulphate precipitated out of solution during early freezing. The dominant nitrogen species was dissolved organic-N which reached 12 g m−3 in Pond 1 just prior to final freeze up. The organic and inorganic forms of nitrogen and dissolved reactive phosphorus increased with increasing conductivity in the ponds. The behaviour of particulate-N and particulate-P mirrored that of chlorophyll a with a peak in March-April and a second higher peak just before final freeze-up. This study provides clear evidence that organisms which persist throughout the year in Antarctic coastal ponds must be capable of surviving much more severe osmotic, pH, temperature and redox conditions than those measured during the summer melt. Deoxygenation, pH decline and H2S production, however, point to continued respiratory activity well into the dark winter months.

Healthy samples of Grimmia antarctici (turf and cushion ecodemes), Ceratodon purpureus, Bryum pseudotriquetrum and Cephaloziella exiliflora were collected in late summer in Wilkes Land together with senescing and dead G. antarctici material. Plant material was subjected to leaching in water and up to 16 freeze-thaw cycles. Gas chromatography revealed that following 16 days immersion, loss of carbohydrates (mainly glucose and fructose) was relatively low (c. 10–29% of the total sugar pool) for healthy material, with the loss of 69% from the dead G. antarctici material. Freeze-thaw cycles greatly increased rates of sucrose leakage and led to a 2–3 times rise in total sugar loss in all samples except the dead brown tissue which was not significantly different from the leached control treatment. After 16 freeze-thaw cycles Bryum pseudotriquetrum had lost 65% of total sugar pool. Losses for other species were below 28%. Differential thermal analyses showed freezing points of tissue varied from −8.3 to −3.5°C with dead material having the highest freezing temperatures. There was no significant correlation within species of freezing temperature changes with progressive sugar loss. The results are discussed in relation to nutrient cycling, soil microbial activity and the viability of bryophyte species in the Antarctic environment.